The progress of LSI technology is really amazing, and the degree of integration is increasing year by year. Taking an example in dynamic random access memory (DRAM), memory capacity has quadrupled in three years. The product development for 4-megabit DRAM has now been completed, and technical development is now directed to 16-megabit and 64-megabit DRAMs. With the increase in the degree of integration, the dimension of the unit element is minimized, and the minimum dimension is decreasing more and more from 1 .mu.m to the order of submicron. The structure of various IC devices is basically composed of a laminated structure of various types of thin film. For example, the main portion of a MOS transistor is composed of 3-layer structure comprising electrode material, insulating thin film and semiconductor substrate. The capacitor, used for a memory cell of DRAM, has semiconductor 3-layer structure with a high dielectric thin film sandwiched by upper and lower electrode materials. A non-volatile memory element has a 5-layer structure composed of semiconductor substrate, insulating thin film, electrode material, insulating thin film, and electrode material. Thus, the thin film laminated structure is a structure dominating the most important characteristics of the device. Because the thickness of these thin films is increasingly becoming thinner with the miniaturization of the device, the characteristics of these thin films are the important factor to determine the characteristics, yield and reliability of LSI. Therefore, the keypoint for the actualization of ultra-high integration is the technique to form high quality thin film and to produce the laminated structure of thin film with high reliability. Further, this process requires low temperature instead of high temperature of 900-1000.degree. C. as used at present. For example, to produce a capacitor structure using aluminum as a lower electrode, the temperature to form an insulating film and electrode on it must be lower than the melting point of aluminum (about 630.degree. C.) for instance, 500-550.degree. C. or less--or more preferably, 400.degree. C. or less. For accurate control of N-type or P-type impurities, it is necessary to reduce the process temperature to 700.degree. C. or less.
In the following, description will be given on the method to produce a conventional type thin film laminated structure, taking an example in the manufacturing process of a DRAM memory cell. FIG. 23 is a schematic drawing showing the sectional structure of a memory capacitor unit of a DRAM memory cell as formed by the conventional technique. To produce this structure, field oxide film 2303 is formed on silicon substrate 2302, and the surface of silicon substrate 2302 of memory capacitor forming portion 2301 is exposed. Then, SiO.sub.2 film 2304 of about 100 .ANG. is formed by thermal oxidation at 900.degree. C. Thereafter, polycrystal silicon thin film 2305 is deposited by CVD method, and a memory capacitor is produced through the patterning into the predetermined shape. In this process, after the surface of silicon substrate 2302 is exposed by etching with dilute HF solution, the wafer is placed into a thermal oxidation furnace to grow the oxide film. After the wafer is taken out of the furnace, it is placed into a CVD apparatus and polycrystal silicon film 2305 is deposited, and this is processed to the predetermined pattern. Namely, the interface of each thin film comes into contact with atmospheric air because each thin film composing the laminated structure is formed in a separate apparatus in the normal process. For this reason, the interface is contaminated by adsorption of adsorptive contaminants in the gas in the atmospheric air, and this results in the instability and variation of isolation voltage or other characteristics of thin film oxide film. The oxide film of 100 .ANG. is the insulating film to be used for 1-megabit DRAM. For 4-megabit or 16-megabit DRAM, it is necessary to have a thin film of 50 .ANG. or thinner, and the problem of interface contamination is an important and serious issue for the decrease of isolation voltage or the reliability of thin film oxide film. In some cases, silicon nitride film (Si.sub.3 N.sub.4) thin film having a higher dielectric constant than thermal oxide film of Si (SiO.sub.2) is used as capacitor insulating film 2304 of DRAM. Because it is very difficult to form Si.sub.3 N.sub.4 film through direct nitriding of silicon, Si.sub.3 N.sub.4 film deposited by LPCVD method is used. Normally, thin film formed by depositing has poor characteristics in the interface with silicon and there are more defects such as pinholes. Accordingly, after the silicon surface is processed by thermal oxidation, the characteristics of interface with Si is improved by depositing Si.sub.3 N.sub.4 film, and pinholes are filled up by thermal oxidation after Si.sub.3 N.sub.4 film is deposited. In such a process, the final capacitor structure is a 5-layer laminated structure composed of Si, SiO.sub.2, Si.sub.3 N.sub.4, SiO.sub.2 and poly-Si (polycrystal silicon), this means that there are four interfaces to be exposed to atmospheric air, and it is very difficult to prevent the contamination. Also, it is almost impossible to carry out the process at low temperatures because thermal oxidation is usually performed at the temperature of 850.degree.-900.degree. C.
To produce and utilize ultra-high integration in the future, it is very important to establish the technique to produce the laminated structure of very thin film at low temperatures and with no possibility to induce contamination on the interface.